Residual Byte Count; Residual Buffer Address - Adaptec AHA-1740A Technical Reference Manual

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Code Description
04 Condition Met (For Search Data and Pre-Fetch SCSI Commands)
10 Intermediate (For Linked SCSI Commands)
14 Intermediate Condition Met
18 Reservation Conflict
When this field contains 02 (check condition) and the Sense Information Stored flag
(Status Word, bit 9) is set to zero, a state of contingent allegiance exists for the tar-
get. All outstanding operations for the associated target queued in the host adapter
and/or the target is suspended. Any control blocks for the associated target received
after contingent allegiance occurred and before the Read Sense Information com-
mand will be accepted and queued by the host adapter, but not executed until the con-
dition is cleared. The contingent allegiance condition is cleared by sending a read
sense information control block for the associated target. It is also cleared by reset-
ting the host adapter or by issuing a bus device reset to the associated target.
If the target returns busy status (Code = 08h), the host adapter will retry the com-
mand indefinitely. This status will be reported only when the command was aborted
by the host while the host adapter was attempting retries.
If the target returns queue full status (Code = 28h), the host adapter will queue the
command internally, therefore, this status will never be reported to the host. If the
host adapter's internal memory is full, the control block will be rejected with Host
Adapter Queue Full status (Status Word, bit 3).

Residual Byte Count

The residual byte count is a 32-bit field (least significant byte first) that contains the
number of bytes that remain to be written from, or read into, the host memory buffer
most recently used to transfer data. This field is valid only if the Data Underrun or
Data Overrun flags (Status Word, bits 1 and 5, respectively) are set to one. If the
Data Overrun flag is set to one, this field will be set to zero.
If Scatter/Gather was enabled for the associated control block, then this field con-
tains the number of remaining bytes for the most recently used segment in the Scat-
ter/Gather list.
If Scatter/Gather was not enabled for the associated control block, then this field con-
tains the number of remaining bytes for the entire transfer count specified in the
data length field of the control block.

Residual Buffer Address

The residual buffer address is a 32-bit field (least significant byte first) that contains
the physical host memory address identifying the buffer last read from or written to.
This field is valid only if the Data Underrun or Data Overrun flag (Status Word, bits
1 and 5, respectively) is set to one.
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AHA-1740A/1742A/1744